Islamic theology

'Ilm al-kalam (literally 'the science of debate') denotes a discipline of Islamic thought generally referred to as 'theology' or (even less accurately) as 'scholastic theology'. The discipline, which evolved from the political and religious controversies that engulfed the Muslim community in its formative years, deals with interpretations of religious doctrine and the defence of these interpretations by means of discursive arguments.

The rise of kalam came to be closely associated with the Mu'tazila, a rationalist school that emerged at the beginning of the second century ah (seventh century ad) and rose to prominence in the following century. The failure of the Mu'tazila to follow up their initial intellectual and political ascendancy by imposing their views as official state doctrine seriously discredited rationalism, leading to a resurgence of traditionalism and later to the emergence of the Ash'ariyya school, which attempted to present itself as a compromise between the two opposing extremes. The Ash'arite school gained acceptability within mainstream (Sunni) Islam. However, kalam continued to be condemned, even in this 'orthodox' garb, by the dominant traditionally-inclined schools.

In its later stages, kalam attempted to assimilate philosophical themes and questions, but the subtle shift in this direction was not completely successful. The decline of kalam appeared to be irreversible, shunned as it was by traditionalists and rationalists alike. Although kalam texts continued to be discussed and even taught in some form, kalam ceased to be a living science as early as the ninth century ah (fifteenth century ad). Attempts by reformers to revive it, beginning in the nineteenth century, have yet to bear fruit.

The term kalam has usually been translated as 'word' or 'speech', but a more appropriate rendering in this context would be 'discussion', 'argument' or 'debate'. Those who engaged in these discussions or debates were referred to as mutakallimun (those who practise kalam or debate). The term has special significance in that traditionalists disapproved of these discussions, arguing that the early Muslims were not known to have indulged in them. Those who dabbled in such debates were said to have 'spoken about' or 'discussed' (takallma fi) 'forbidden' topics. The proponents of kalam also liked to refer to it as 'ilm al-usul (the science of basic principles) or 'ilm al-tawhid (the science of [affirming God's] unity), and it is under this latter name that some of its topics continue to be taught and discussed in Muslim educational institutions today.

The rise of 'ilm al-kalam was a result of the many controversies that had divided the Muslim community in its early years. Although the emergence of Islam was characterized by polemics with polytheists and followers of earlier revelations, controversies over fundamental religious questions were deemed irreverent by early Muslims, especially during the lifetime of the Prophet. However, disputes (mainly political) broke out immediately following the death of the Prophet, and again following the tragic events that led to the murder of the third Caliph Othman in ah 35/ad 656, this time heralding the breakdown of the political system established after the Prophet's death.

In a community that defined itself in terms of its religious identity, political disputes inevitably turned into theological ones. The political struggles over who should lead the Muslim community gave rise to three major competing groups: the Khawarij, who opposed the fourth Caliph 'Ali and rejected the compromises he made with his opponents; the Shi'a, who supported 'Ali; and the Murjiya, who tried to remain neutral. These groups attempted to influence a wider Muslim community dominated by a loose grouping of mainstream schools, mainly conservative or traditionalist, known collectively as ahl al-sunna wa'l-jama'a (the proponents of the [Prophet's] traditions and consensus).

The term khawarij (literally 'rebels') first referred to a group of dissidents who rebelled against the leadership of 'Ali following the inconclusive battle of Siffin (ah 37/ad 658) between 'Ali and his challenger, Mu'awiya, and later evolved into a distinct antiestablishment tendency. The Khawarij had neither a unified leadership nor a settled doctrine, and was primarily a militant political tendency with an uncompromising attitude. The core of their views revolved around the nature of legitimate leadership and the conditions for salvation. Although the Khawarij's uncompromising views condemned them to a marginal existence, their impact on the general body of the Muslim community was significant. Most of the major schools of thought that emerged did so in response to one or other of their assertions, especially on the issues of leadership and the 'status of sinners'.

At the opposite pole stood the Shi'a (party) of 'Ali. Unlike the Khawarij, who defied all authority, the Shi'a believed in the undisputed authority of the divinely ordained imam (leader). The position of 'Ali as imam and successor to the Prophet was vouchsafed by revelation and was not a matter of opinion. Each imam would then designate his successor by virtue of the divine authority vested in him. In theory, Shi'ism should not have encouraged much theological speculation, since it sought to perpetuate and reproduce the authority of the Prophet and vest it in the person of the living imam, who had direct access to the divine truth. In practice, however, Shi'ism did indulge in theological speculation, especially with the emergence of the doctrine of the Absent Imam, which referred the burden of seeking the truth back to the community.

In between these two extremes, a large number of intermediary positions were espoused, notably that of the Murjiya. This group refused to condemn the perpetrators of grave sins (a euphemism for usurpers of power) as unbelievers, but neither did it want to absolve them, arguing that the matter should be left to God to judge in the hereafter. Murjiism was also associated with political neutrality, and an implied tacit support for the status quo.

While the above three groups were political in origin, adopting theological arguments to support their politics, there were also groups of which the primary focus was on theology. The earliest of these was the Qadariyya (the name, meaning proponents of qadar, or predestination, was a misnomer for this school which supported freedom of the will). This school argued for the absolute freedom of the will. God, its members said, would not put us human beings under obligation to act righteously if we did not possess the power to choose our course of action.

Diametrically opposed to this school were the Jabriyya (determinists). Their most prominent spokesman was Jahm ibn Safwan (d. ah 128/ad 746), who taught that no attributes could be predicated of God except for creation, power and action, since any attribute that could be predicated of creatures was not fit to be predicated of the Creator. As God is the sole Creator and actor, our actions are also authored by him alone; therefore, we as persons have no control over our actions and no free will. Jahm also said that since God could not be described as a speaker, the Qur'an could not be said to be his word, except in the sense of having been created by him.

These earlier schools were amorphous groupings, very fluid both in membership and doctrine. With the exception of the Shi'a, who later developed into a number of coherent sects, these tendencies either faded away or merged into other tendencies. The rise of a systematic theological discourse had to await the emergence of the Mu'tazila. The association of kalam with the Mu'tazila, who were characterized by their elitism and their militant rationalism, determined its course and its eventual fate. The Mu'tazila attempted to systematize religious doctrine into a rational schema centred on the affirmation of God's absolute unity and absolute justice (see Ash'ariyya and Mu'tazila).

However, the Mu'tazila's elitism and their irreverent quest for 'a reason for everything,' to paraphrase al-Shahrastani, alienated the more conservative mainstream tendencies. The latter questioned the very possibility of a theological discourse of the type advocated by the Mu'tazila, regardless of content, viewing such discourse as at best superfluous and at worst a heretical deviation. This attitude was expressed succinctly by Malik ibn Anas (d. ah 179/ad 795), the leading jurist of Medina, when asked to explain how God could be said to have 'established himself on the Throne' as mentioned in the Qur'an: 'The establishment is known, the modality is unknown, the belief in it is obligatory and asking questions about it is an unwarranted innovation.' On the question of divine justice, the traditionalists rejected the Mu'tazila's attempts to impose human and rational concepts of justice on God. It would be meaningless to speak of justice in this context, since God was the absolute sovereign and absolute master of all His creation, which meant that anything which He did was by definition just (see Omnipotence §5).

The struggle between the two trends came to a head in the 'creation of the Qur'an' controversy which erupted in the first half of the third century ah (ninth century ad). The 'Inquisition' which the Mu'tazila instigated with the help of the ruler of the day, the Caliph al-Ma'mun (ah 198-218/ad 813-33), to enforce this and related doctrines proved disastrous, not only for the Mu'tazila but also for the discipline of kalam itself. In spite of being reclaimed for orthodoxy by Abu'l-Hassan al-Ash'ari and others, the science and art of arguing matters of faith with appeal to unaided human reason fell into disrepute and went into a decline from the start of the sixth century.

Classical definitions tended to emphasize the apologetic function of kalam, probably in order to appease traditionalist critics. Al-Iji speaks of
'a science which makes it possible to prove the truth of religious doctrines by marshalling arguments and repelling doubts' (al-Mawaqif: 7). Kalam, however, has also been the arena on which battles over what constituted true religious doctrine were fought between rival schools.

The subject of kalam, to quote al-Iji again, was
'knowledge on which the proofs of religious doctrines depend, directly or indirectly' (al-Mawaqif: 7). It was also said to deal with 'usul (basics), as opposed to furu' (subsidiary issues). These included the fundamentals of religious belief, such as God, his attributes and acts, the proofs of religious doctrines, the nature of the universe and our place in it.

The first issue that divided Muslims into opposing schools was the question of political authority and its legitimacy. Most traditionalist and mainstream schools accepted the actual procedures adopted to elect the first four caliphs as normative, thus affirming that a ruler gains legitimacy by being freely elected by the influential members of the community. The Khawarij accepted the procedures up to the election of the third caliph, but then added that even an elected caliph should be removed if he deviated from his mandate. The Khawarij also held that any qualified individual was fit to be caliph, provided the community at large approved of him. The traditionalists narrowed the field of selection to the Prophet's tribe, Quraysh, while the Shi'a narrowed it still further to the Prophet's family, in particular his son-in-law 'Ali and the latter's descendants. Shi'ism argued that political leadership, being the most important religious institution, could not be left for human reason to determine.

The second major issue to be discussed within kalam was the status of the grave sinner. The Khawarij started this debate by arguing, contrary to mainstream opinion, that any person who committed a grave sin automatically became a non-believer, thus forfeiting all rights and protections afforded by Islamic law. The Murjiya argued for the withholding of judgment while tending to widen the interpretation of who could qualify as a believer; the Mu'tazila held that such a person was in an intermediate position, being neither a Muslim nor an unbeliever.

The third major issue discussed in kalam was freedom of the will. The Mu'tazila and Qadariyya both came out unequivocally in support of freedom of the will. They held that we are the creators of our own acts, for otherwise God would be committing a grave injustice if he were to punish those who had no choice in what they did (see Evil, problem of §3; Free will). At the other extreme, the Jabriyya held that man could not have any control over his actions, since God was the sole creator and actor. Most other groups tried to strike a balance between these two poles. The Shi'a tended to affirm the freedom of the will and some of them, such as the Zaydiyya, agreed completely with the Mu'tazila on this. Some Shi'a factions, however, qualified their stance by affirming that we are in part compelled because of the chain of causation that triggered our acts. The Khawarij accepted the idea of predestination, holding that God was the Creator of the acts of people, and that nothing occurs which he did not will.

This was also the view of mainstream orthodox and traditionalist groups, who affirmed that the will of God was supreme and that he was the creator of all human acts, whether evil or good; nothing could happen on earth that contradicted his will. This position was later given some nuances by al-Ash'ari, who argued that God created human acts, but we acquired (kasaba) these acts by willing them prior to their creation.

The fourth major issue discussed in kalam was the question of divine attributes. The Jabriyya used the affirmation of the uniqueness of God's attributes to deny the existence of free will. The Mu'tazila developed the idea further, arguing that God could not have attributes in addition to his essence, for this would mean a multiplicity of eternal entities. Later Mu'tazilites, such as Abu'l-Hudhayl al-'Allaf (d. ah 227/ad 842), added that the divine attributes are identical with the divine essence. God's knowledge is not an attribute added to his essence, but is identical with that essence.

Early Shi'ite theologians opposed the Mu'tazila, affirming God's immanence in space and denying his immutability and transcendence of time and space. They held that God's will was also mutable, and ascribed motion to him. God could also be the locus of accidents (hawadith) and was corporeal in some sense. God's knowledge and will could not be eternal, for this would negate human freedom and make accountability redundant. It could also imply the eternal existence of things. Later Shi'ite theologians, however, especially the Zaydiyya, repudiated most of the anthropomorphisms of their predecessors and veered towards Mu'tazilite positions.

Traditionalists (who include the Ash'ariyya) affirmed the reality of God's eternal attributes, which they said were neither identical with his Essence nor distinct from it. They also affirmed the literal sense of apparently anthropomorphic Qur'anic references, such as those to God's 'face', 'hands' and 'eyes', adding that the exact nature of these limbs could not be known.

Related to the issue of divine attributes was the issue of the Qur'an's creation. The Mu'tazila denied that God's words were eternal and affirmed that the Qur'an had to be created; this idea was accepted also by the Khawarij. However, the bulk of the traditionalists (and Ash'ariyya) rejected this view, arguing that one could not describe God's speech as created because this would mean that God was subject to changing states. Speech (kalam) was one of God's eternal attributes, and the Qur'an, being God's word, could not be said to be created or uncreated. Some early Shi'i theologians, in particular Hisham ibn al-Hakam (d. c.ah 200/ad 816), developed a more sophisticated version of the latter argument, saying that the Qur'an (or God's word) could not be described as creator, created or uncreated, because an attribute, being an adjective, could not have another adjective predicated of it. Similarly, one could not say about God's attributes that they were eternal or contingent.

Besides these main themes, kalam touched on related issues such as whether God could be seen in the hereafter (with the Mu'tazila rejecting this, while their opponents affirmed beatific vision), the nature and limits of faith, whether hellfire and paradise were everlasting, and the nature and limits of God's knowledge, will and power. Starting with 'Allaf, some philosophical themes were introduced into kalam, in particular the discussion of such questions as the nature and classification of knowledge and the nature of movement, bodies and things. It even went on to discuss questions belonging to other sciences, such as biology, psychology and chemistry, as well as various logical investigations. However, this expansion of the scope of kalam coincided with its decline and did not lead to significant advances in any of these areas.

Kalam generally dealt either with attempting to justify religious beliefs to reason, or with employing reason to draw new conclusions and consequences from these beliefs. Its doctrines comprise three major components: the articulation of what a school regarded as fundamental beliefs; the construction of the speculative framework within which these beliefs must be understood; and the attempt to give coherence to these views within the accepted speculative framework.

The various schools of kalam agreed with the traditionalists in accepting the authority of texts as the basis of the first component. They disagreed, however, about the extent to which these texts should be subjected to 'rational' analysis. Traditionalists had always suspected that the 'reason' being referred to was in fact the suspect intellect of infidel heretics; why else would a believer want to drag the articles of faith in front of the court of human reason, fallible and limited as it was? The traditionalist suspicion of non-Islamic influences behind every early kalam-ist 'heresy' has been reproduced by modern researchers, who seek an alien origin for every idea expressed in kalam (see Orientialism and Islamic philosophy). However, the impact of non-Islamic influences on the evolution of the schools of kalam, though undeniable, could easily be exaggerated. Many of kalam's early themes, such as the status of the sinner or the question of political legitimacy, appear to have arisen within a purely Islamic context.

Regarding the second component, the speculative framework, the early groups did not erect elaborate systems. It is with the Mu'tazila that we find the first attempt to construct such a system, based on their five principles (divine unity, divine justice, divine warnings, the intermediary status and the enjoining of virtue and discouragement of vice). The Mu'tazila also brought with them an attitude of absolute confidence in human reason and a consequent lack of reverence for the authority of texts, which they regularly challenged.

The third component, the cohesion of views within the speculative framework, also came into prominence with the Mu'tazila, who tried to systematize the body of religious beliefs and harmonize its components, provoking intense controversy as they attempted to reinterpret key elements of orthodoxy in order to achieve this. The attempts at systematization inevitably led to the raising of philosophical questions. Later Mu'tazilite thinkers, such as al-'Allaf and Ibrahim al-Nazzam (d. ah 231/ad 846), reflected in their theses the influence of translated Greek philosophical texts and propagated a worldview influenced by Hellenistic speculation (see Greek philosophy: impact on Islamic philosophy). The Ash'arite school, especially al-Juwayni and al-Ghazali, formally introduced the tools of Aristotelian logic into the methodology of kalam (see Logic in Islamic philosophy).

This introduction of philosophical themes and methods and the employment of formal logic in the Aristotelian tradition represented a significant development in kalam. Prior to that, kalam arguments had used textual and linguistic analysis as their central tools. However, in spite of these forays into philosophical speculation and the employment of Aristotelian logic, kalam remained firmly anchored in a specifically Islamic framework. Authoritative texts were routinely cited to clinch an argument, while an accusation of heresy was thought to be a conclusive refutation of any argument.

Even without the help of philosophy, however, Ash'arism brought to kalam a trenchant scepticism that had a healthy impact on the field of rational argument. This scepticism was carried to great lengths by al-Ghazali, who used it to demolish the confused Neoplatonism of the Hellenizing philosophers. This approach had the potential to contribute much more to the advancement of knowledge than the dogmatic reiteration of philosophical theses, but that potential was not to be realized because the kalam practitioners were more interested in demolishing their opponents' arguments than in constructing viable alternatives.

The decline of kalam proceeded apace from the fifth century ah (eleventh century ad), settling by the ninth century ah (fifteenth century ad) into ossified dogmatic texts that, to paraphrase al-Ghazali, taught the dogma as well as its formal 'proof', which was not the same thing as proving it to be true. This decline of kalam became too apparent to ignore even by its practitioners. Al-Iji comments that the aversion to the discipline in his time meant that engaging in it had become
'among the majority a reprehensible thing' (al-Mawaqif: 4). Ibn Khaldun, another Ash'arite writing during the same period (c.ah 779/ad 1377), deplored the fact that kalam had deteriorated and become confused with philosophy, on top of being redundant because the heresies it was meant to combat had become extinct.

However, kalam's problem was not so much its fusion with philosophy as its failure to evolve into a fully-fledged philosophical system with its own complete frame of reference. The possible evolution in this direction had been interrupted by a number of factors. First, there was the rift that developed between kalam as a discipline and philosophy proper; this was caused in part by the decline of the Mu'tazila, the natural allies of philosophy. In addition, the failure of the Mu'tazila to develop a common language with their opponents, thus turning kalam into a kind of sectarian pursuit rather than a discipline, was duplicated by the philosophers. The quasi-religious reverence shown by early Muslim philosophers to Greek texts put them at odds with mainstream thought, causing them to behave like just another sect. This limited the interaction between kalam and philosophy, as each treated its basic principles and texts as 'sacred' rather than as theses which could themselves be questioned. The rise of philosophy thus came both at the expense of kalam and in opposition to it, and this antagonism damaged both.

Kalam was also undermined by the rise of pro-traditionalist tendencies within the discipline itself. It was difficult to reconcile vigorous rationalist discourse with the traditionalist position, which discouraged questioning in many key areas and even counselled the acquiescence in apparent contradictions. At another level, the resurgence of traditionalism under Ahmad ibn Hanbal and subsequent revivals under Ibn Taymiyya and his disciples was anti-kalam, rejecting not only its theses but its methods as anathema. Rearguard actions fought by Ash'arite and Maturidi scholars of the fifth to eighth centuries ah (eleventh to fourteenth centuries ad), failed to stem this tide and revive kalam. Finally, complementing the effect of traditionalism was the rise and popularity of Sufi mysticism (see Mystical philosophy in Islam). Although opposed by traditionalism, Sufism was also anti-rationalist and had also grown at the expense of kalam and philosophy.

With all these powerful forces deployed against it, the decline of kalam was inevitable. The early schools of kalam all became extinct, but traces of their teachings remain embedded within the doctrines of the six main schools of Islamic jurisprudence. The two main Shi'a schools (the Ithna 'Ashriyya and Zaydiyya) have inherited some aspects of Mu'tazilite rationalism and doctrines. Shi'ism has also been more successful in assimilating Sufi tendencies and more reconciled to philosophical discourse. The Hannafiyya became closely associated with the Maturidi school of kalam. The Shafi'iyya espoused Ash'arism as a general rule, as did the Malikiyya, although with less enthusiasm. The Hanbalites favoured an anti-rationalist and anthropomorphic position, distrusting kalam altogether.

The manifest failure by the various schools of 'ilm al-kalam either to create for itself a secure niche among the religious sciences, or to attain the status of a philosophical system independent of religious dogma, was not merely the result of the arrogant elitism of the Mu'tazila and their political opportunism. A deeper malaise afflicted the rationalist schools, reflected in their methodological confusion and, simultaneously, their militant dogmatism. Ironically, it was left to the traditionalist theologians, notably al-Ash'ari, al-Ghazali and Ibn Taymiyya, to introduce some healthy scepticism into the discourse by revealing some of the more glaring self-contradictions of the rationalist dogmas. However, the traditionalists not only inherited some of the confusion of their opponents, they also added some of their own.

An interesting example of this confusion was the uncritical acceptance by all schools of kalam of the Neoplatonic premise that the perfection of God as an eternal being meant that he could not be the locus of accidents (hawadith), while rejecting its logical consequence: God's remoteness from his creation and the impossibility of his day-to-day involvement with it. The confusion which this self-contradiction generated was then cited by many as a proof of how inadequate reason was in dealing with matters of faith. The choice offered the community was thus between rationalists who discredited themselves by their manifest errors, and traditionalists who exploited these errors and confusion to discredit rational thought as such.

The attacks of self-doubt brought by turmoil of modern times have created an atmosphere for a revival of Islamic theology and philosophy (see Islamic philosophy, modern). The pioneers of the modern Islamic revival, such as Jamal al-Din al-Afghani and Muhammad 'Abduh, tried to revive Islamic philosophy and kalam; al-Afghani indeed insisted that the revival of philosophy was an indispensable precondition for any Islamic revival. A century later, the tides of revival have drowned all attempts at philosophizing. On the face of it, the vibrancy and capacity for self-regeneration of the Islamic faith seem to be proportionately resistant to the emergence of systematic theologies and philosophies.

However, in spite of the self-satisfaction on the part of orthodoxy, on the grounds that history has condemned the systems rejected by Islam as fatally flawed and confused, there can be no substitute for setting up a viable worldview and a defensible theology, which would remain fallible and incomplete but still an essential guide for life. It would seem that if Islam is to continue as a living system, 'ilm al-kalam (or something like it) may need to be revived, so that progress towards Muslim self-understanding, interrupted some six centuries or so ago, can be resumed.

References and further readings

Abdel Haleem, M. (1996) 'Early Kalam', in S.H. Nasr and O. Leaman (eds) History of Islamic Philosophy, London: Routledge, ch. 5, 71-88. (Description of some of the variety among early theologians in Islam.)

Anawati, G. and Gardet, L. (1950) Introduction à la théologie musulmane (Introduction to Muslim Theology), Paris: Vrin. (One of the most thorough discussions of kalam in a Western language.)

Corbin, H. (1993) History of Islamic Philosophy, trans. L. Sherrard, London: Kegan Paul International. (While most introductions tend to neglect Shi'i contributions to kalam, this one redresses the imbalance, with an extensive bibliography.)

al-Farabi (c.870-950) Ihsa' al-'ulum (Enumeration of Sciences), ed. A. González Palencia, with Spanish translation ( Catálogo de las ciencias), Madrid: Maestre, 1932. (A survey of the state of learning in the fourth century ah (tenth century ad), offering an assessment of kalam in its heyday from a philosophical perspective.)

Farrukh, O. (1979) Tarikh al-fikr al-'arabi ila ayyam Ibn Khaldun (The History of Arab Thought up to the Time of Ibn Khaldun), Beirut: Dar al-'Ilm li'l-Malayin. (A general introduction to kalam and Islamic philosophy with a comprehensive bibliography of Arabic sources.)

al-Ghazali (c.1111) Iljam al-'awam 'an 'ilm al-kalam (Restraining Commoners from Kalam), ed. M. al-Baghdadi, Beirut: Dar al-Kitab al-'Arabi, 1985. (Al-Ghazali's final attacks on kalam, arguing that it would be harmful for most people to indulge in it.)

Goldziher, I. (1910) Vorlesungen über den Islam (Introduction to Islam), Heidelberg; trans. A. Hamori and R. Hamori, Introduction to Islamic Theology and Law, Princeton, NJ: Princeton University Press, 1981. (An early introduction that still stands out in spite of minor flaws that are a feature of its times.)

Hallaq, W. (1993) Ibn Taymiyya Against the Logicians, Oxford: Clarendon Press. (A translation of a summary of Ibn Taymiyya's al-Radd 'ala al-mantiqiyyin with a good introduction to the latter's crusade against logic and philosophy.)

* al-Iji (before 1355) Al-mawaqif fi 'ilm al-kalam(Book of Stations on Kalam), Cairo: Dar al-'Ulum. (Textbook which reflects the culmination of the rapprochement between philosophy and kalam in later Maturidi thought.)

Macdonald, D. (1903) Muslim Theology, Jurisprudence and Constitutional Theory, New York: Scribner's. (A scholarly introduction that deserves its status as a classic in the field.)

Madelung, W. (1985) Religious Schools and Sects in Medieval Islam, London: Variorum Reprints. (A reprint of essays published by the author over many years covering various aspects of kalam and the evolution of religious thought in Islam.)

Montgomery Watt, W. (1948) Free Will and Predestination in Early Islam, Edinburgh: Edinburgh University Press. (A discussion of the beginning of theological thinking in Islam.)

Pavlin, J. (1996) 'Sunni Kalam and Theological Controversies', in S.H. Nasr and O. Leaman (eds) History of Islamic Philosophy, London: Routledge, ch. 7, 105-18. (Account of some of the most important Sunni theologians.)

al-Tusi (c.1270) Talkhis al-muhassal (Summary of [al-Razi's] Muhassal), ed. T.A. Sa'd, Beirut: Dar al-Kitab al-'Arabi. (A summary and commentary on al-Razi by a leading Shi'ite scholar who favoured Neoplatonist philosophy more than did al-Razi and other practitioners of kalam.)

Wensinck, A. (1932) The Muslim Creed, Cambridge: Cambridge University Press. (An early introduction which influenced a large number of writers on the subject.)